LINWOOD — Three of the four southern New Jersey football players killed in a car crash last summer tested positive for chemicals found in marijuana, a newspaper reported today after obtaining the results through a public-records request.

Drug tests showed THC and carboxy in the blood of driver Casey Brenner, 17, of Northfield, and passengers Edgar Bozzi, 17, of Somers Point, and Dean Khoury, 15, of Linwood, The Press of Atlantic City reported.

Toxicology results for the fourth player killed, Nicholas Conner, 16, of Northfield, were negative.

Eight Mainland Regional High School players were in the vehicle when it crashed on the Garden State Parkway in August 2011. They were on their way to a team breakfast following the last practice of the summer.

The newspaper quoted an expert unaffiliated with the investigation who said the levels of those substances found in the bloodstream could lead to impairment.

Richard Saferstein, the former chief chemist at the New Jersey State Police crime lab and now a Mount Laurel-based forensic science consultant, told the newspaper that a concentration of THC at a level lower than that found in the victims' blood can lead to impairment of motor function.

Saferstein said a number of factors, including how often someone smokes marijuana, can affect THC levels. He said the chemical usually remains in the blood for two to four hours, although that can vary.

The newspaper reported that a substance police believed to be marijuana was found at the crash site.

State police said days after the accident that the substance was sent to a lab for testing, but on Wednesday they told the newspaper those results will not be released. Any record of testing of the substance would be considered a criminal investigatory record and would not be releasable through the Open Public Records Act, state police detective Ismael Vargas said.

Four of the families filed tort claims last year against the New Jersey Turnpike Authority, the South Jersey Transportation Authority, Atlantic County, Egg Harbor Township and the state, alleging dangerous conditions were allowed to exist on the roadway. The claims are not lawsuits but secure the rights of the families to sue.